Toy building block



FIG. 1 is a front left perspective view of a toy building block showing the claimed design;

FIG. 2 is a front right perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof. 

CLAIM The ornamental design for a toy building block, as shown and described. 